I use
CML Electronics circuit boards to control signal on TheChaleur
& Restigouche.
These CML SIGM 20 circuits control NJ Intenational signals. NJ
International web site doesn't do credit to the signals that they have
available. These led signals are available in a wide range of
models. When buying signals, make sure that you buy one or two from
different manufactures in order to compare. Home layout uses of signals
are quite different from prototype signals. On a home layout, signals
are mostly viewed at an angle. Detection is done with resistance axles.
I use Digitrax BDL 168 to complete the detection.

The above and lower
pictures show two trains meeting. The two GP-40-2W wait in the passing
siding as it has a red signal. Notice that the top head of the signal
indicates green which means that Engine 5563 is free to continue on the main
line while the other trains waits in the passing siding.